Donor sheet, color filter, organic EL element and method for producing them

ABSTRACT

A donor sheet for transferring an image pattern to an image receiving element by a thermal imaging process using laser beam, comprising a base having formed in order on the base a light-to-heat conversion layer, and a transfer layer containing an image component which is melted by heating due to an action of the light-to-heat conversion layer and transferred to the image receiving element in a patterned form, in which the image component of the transfer layer contains an ink-repellent or solvent-repellent compound in an optimized amount. Using the donor sheet, it becomes possible to produce an separation member such as partition pattern and black matrix of a color filter by a shortened manufacturing step with ease and accuracy at high contrast, and can impart excellent ink repellency to the separation member.

TECHNICAL FIELD

The present invention relates to a thermal imaging process using laserbeam and, more particularly, to a donor sheet (so-called “image formingsheet”) used in the process, and an optical element formed by using thedonor sheet, particularly, color filter and organic EL element and theirproduction methods. Particularly, the present invention relates to amethod of producing a separation rib of a color filter, a black matrixof a liquid crystal display device and a partitioning wall (bank) of anorganic EL element. A thermal imaging process using laser beam isgenerally referred to as a laser beam thermal transfer method or LITI(Laser-induced Thermal Imaging) method.

BACKGROUND ART

As is well known, an ink-jet recording method is one method of printingmethods and is utilized in various fields of image formation becausemulti-color fine images can be formed. For example, the ink-jetrecording method is used for formation of a picture element area in theproduction of a separation rib (so-called “partition pattern”) of acolor filter and a black matrix of a liquid crystal display device.

For example, Japanese Unexamined Patent Publication (Kokai) No. 6-347637discloses a method of printing a color pattern between the space ofpartition patterns (black matrix) containing fluorine-based water andoil repellency agents, characterized in that printing is conducted byusing ink having a specific surface tension. In the case of thisprinting method, the partition pattern can be produced by known methodssuch as gravure printing method, photoresist method, thermal transfermethod and the like. Japanese Unexamined Patent Publication (Kokai) No.7-35915 discloses a color filter comprising a transparent substrate, aplurality of picture elements formed at a predetermined position of thetransparent substrate, and a light shielding black matrix between thespace of the picture elements, characterized in that the light shieldingblack matrix is a black resin layer containing a fluorine-containingcompound and/or a silicon-containing compound. In the case of this colorfilter, the black matrix can be formed by using a black photosensitiveresin composition as a starting material according to a photoresistmethod and the following formation of the picture elements can beconducted by a printing method or an ink-jet recording method.

The reason why the black matrix is formed from the black resin layercontaining the fluorine-containing compound and/or silicon-containingcompound in the above-described color filter is as follows. That is,when picture elements are formed by the ink-jet recording method,droplets of ink are ejected and dropped from a head of an ink-jetprinter to an opening portion (picture element area) surrounded by theblack matrix. In that case, ink having very low viscosity and smallsurface tension must be used so as to accurately eject small droplets ofink at high speed and to quickly spread them in a uniform thickness inthe opening portion. Therefore, it becomes necessary to impart inkrepellency (water repellency and oil repellency) to the black matrixitself for the purpose of preventing color mixture caused by leakage ofink from the black matrix. Suitable material includes theabove-described fluorine-containing compound and silicon-containingcompound.

By the way, a conventional method of forming a black matrix has severalproblems. For example, in case where the black matrix is formed from theabove-described black photosensitive resin composition or a similarphotosensitive composition prepared by dispersing black pigments, dyesor metal powders in a resin for the purpose of imparting a lightshielding property according to a photoresist method, it is essential toconduct various treatments such as coating, curing, exposure,development, drying and the like of the resin composition. Therefore,not only the working is complicated, but also problems such ascomplexation of a processing device and increase in manufacturing costoccur. The black matrix is formed from a metal thin film, e.g. thin filmof chromium (Cr) or chromium oxide (CrO₂) in place of the photosensitiveresin composition. In this case, however, a photoresist method must beused for patterning the metal thin film and, therefore, theabove-described problems can not be avoided.

Specifically explaining, the above-described black matrix is usuallyformed through a series of processing steps.

1) A black matrix precursor made of metal, i.e. a thin film of a blackmatrix forming material is formed on a substrate. For example, a thinfilm of Cr or a thin film of Cr and CrO₂ is formed by a sputteringmethod.

2) A photosensitive resin composition is coated on the thin film of theblack matrix in a predetermined film thickness. Generally, aspin-coating method is used as a coating method.

3) The photosensitive resin composition is cured by prebaking in an ovento obtain a resist film.

4) The resist film is subjected to pattern exposure via a mask with adesired pattern of a black matrix. As an exposure light source, anultraviolet lamp and the like is used.

5) The unexposed area of the resist film is removed, for example, bydeveloping with an alkali developer.

6) Using, as a mask, the resist film remained without being removed, theexposed area of the underlying thin film of the black matrix precursoris removed by dissolving with an etching solution.

7) The residue on etching is removed by washing. As a result, a blackmatrix having a desired pattern is obtained.

8) The resist film used as the mask is removed.

Alternatively, the black matrix can also be formed by dispersing thelight shielding material such as black pigment in the photosensitiveresin composition. In this case, the black matrix precursor, i.e. metalthin film is not used and a glass substrate is used as the substrate.Accordingly, the steps (1) and (6) among the above-described processingsteps are omitted and curing is conducted by post baking in place ofremoval of the resist in the step (8) and the cured resist is remainedas it is.

As is understood from the above description, in the method of formingthe black matrix by using a photoresist method, six to eight processingsteps are generally required, whereby processing devices such as coatingdevice of the resin composition, baking device, exposure device and thelike are also required. A method of forming a black matrix of metalaccording to a deposition method, electroless plating method or the likewithout using a photoresist method is also considered, however, aproblem about the processing step is remained and there is not a meritas compared with the photoresist method.

Under these circumstances, it is desired to provide a method ofproducing a black matrix, capable of directly forming the black matrixon a substrate without making processing steps and processing devicescomplex.

By the way, Japanese Unexamined Patent Publication (Kokai) No. 6-347637cited above discloses a possibility of formation of a partition patternaccording to a thermal transfer method, but it is not specificallydescribed. Accordingly, a method of producing a color filter elementusing a LITI method described in U.S. Pat. No. 5,521,035 will bereferred herein with regard to this respect. According to this method, ablack matrix can be formed in a desired pattern by transferring acoloring agent from a black donor sheet containing a fluorine surfactantonto a substrate of a color filter element, utilizing thermal transferdue to laser beam. According to the black matrix using the LITL method,satisfactory results can be obtained as compared with a conventionalphotoresist method, but it is desired to further improve waterrepellency and oil repellency.

Further, the ink-jet recording method has been utilized in the formationof a luminescent layer made of an organic compound in the production oforganic EL elements and devices. For example, International PublicationWO98/24271 discloses a method of manufacturing an organic EL element,comprising the steps of: forming pixel electrodes on a transparentsubstrate; forming on said pixel electrodes by patterning at least oneluminescent layer having a certain color and made of an organiccompound; and forming a counter electrode opposing the pixel electrodes,wherein the formation of the luminescent layer is performed by means ofan ink-jet method.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to solve the above-describedproblems of the prior art and to provide a donor sheet, which canproduce an separation member of an optical element, e.g. partitionpattern and black matrix of a color filter, by a shortened manufacturingstep with ease and accuracy at high contrast, and can impart excellentink repellency, i.e. water repellency and oil repellency to theseparation member.

It is another object of the present invention to provide a method ofproducing an separation member such as black matrix, partition pattern,etc., capable of directly forming the insulation member on a substrateusing the donor sheet of the present invention without making processingsteps and processing devices complex.

It is still another object of the present invention to provide a colorfilter provided with the separation member formed using the donor sheetof the present invention.

It is a further object of the present invention to provide a method ofproducing the color filter provided with the separation member formedusing the donor sheet of the present invention.

It is, a still another object of the present invention to provide anorganic EL element having partitioning walls formed upon use of thedonor sheet of the present invention, and a production method thereof.

The above-described objects as well as other objects will becomeapparent from the following detailed description.

The present invention provides, in an aspect thereof, a donor sheet fortransferring an image pattern to an image receiving element by a thermalimaging process using laser beam, comprising a base, a light-to-heatconversion layer, and a transfer layer containing an image componentwhich is molten by heating due to an action of the light-to-heatconversion layer and transferred to the image receiving element in apatterned form, said layers being formed in order on the base,characterized in that:

-   -   the image component of the transfer layer contains an        ink-repellent or solvent-repellent compound in an optimized        amount.

In the donor sheet of the present invention, it is preferred that anintermediate layer is disposed between the light-to-heat conversionlayer and the transfer layer. Further, it is preferred that the transferlayer contains an fluorine-containing compound or a silicone compoundalone or in combination.

The present invention provides, in another aspect thereof, a colorfilter comprising a transparent substrate, a plurality of pictureelements disposed on a predetermined position of the substrate, and apartition pattern for separating adjacent picture elements,characterized in that:

-   -   the partition pattern on the substrate is formed by making the        transfer layer of the donor sheet of the present invention and        the surface of the substrate come closely into contact with each        other and transferring the image component of the transfer layer        of the donor sheet in a pattern corresponding to the partition        pattern by a thermal imaging process using laser beam.

In the color filter of the present invention, the picture elements arepreferably formed by forming the partition pattern and applying ink to apicture element forming area using an ink-jet system.

In the color filter of the present invention, the partition pattern canfunction as a separation rib of the color filter, or the partitionpattern itself has a light shielding property in a predetermined leveland functions as a black matrix of a liquid crystal display device.

The present invention provides, in a still another aspect, a method ofproducing a color filter comprising a transparent substrate, a pluralityof picture elements disposed on a predetermined position of thesubstrate, and a partition pattern for separating adjacent pictureelements, which comprises the steps of:

-   -   coating the surface of the substrate to form a thin film of a        black matrix forming material;    -   laying the substrate and a donor sheet of the present invention        one upon another so that the thin film-like black matrix forming        material and the transfer layer of the donor sheet come closely        into contact with each other;    -   irradiating laser beam from the base side of the donor sheet        corresponding to a desired pattern of the black matrix by a        thermal image process using laser beam, thereby to melt the        image component of the transfer layer of the donor sheet with        heating and to transfer the melted image component on the thin        film-like black matrix forming material;    -   removing the exposed black matrix forming material by etching        using, as a mask, the image component transferred to the surface        of the thin film-like black matrix forming material of the        substrate in a patterned form; and    -   filling an opening portion surrounded by the partition pattern        formed from the image component and black matrix as a ground        thereof with ink having a predetermined color using an ink-jet        method, thereby to form picture elements.

The present invention also provide a method of producing a color filtercomprising a transparent substrate, a plurality of picture elementsdisposed on a predetermined position of the substrate, and a partitionpattern for separating adjacent picture elements, which comprises thesteps of:

-   -   forming a thin film-like black matrix in a predetermined pattern        on the surface of the substrate;    -   making the surface of the black matrix side of the substrate and        a transfer layer of a donor sheet of the present invention come        closely into contact with each other;    -   irradiating laser beam from the base side of the donor sheet        corresponding to the pattern of the black matrix by a thermal        image process using laser beam, thereby to melt the image        component of the transfer layer of the donor sheet with heating        and to pile up the melted image component on the black matrix;        and    -   filling an opening portion surrounded by the formed partition        pattern with ink having a predetermined color using an ink-jet        method.

Furthermore, the present invention provides a method of producing acolor filter comprising a transparent substrate, a plurality of pictureelements disposed on a predetermined position of the substrate, and alight shielding partition pattern for separating adjacent pictureelements, which comprises the steps of:

-   -   laying the substrate and a donor sheet of the present invention        one upon another so that the thin surface of the substrate and        the transfer layer of the donor sheet come closely into contact        with each other;    -   irradiating laser beam from the base side of the donor sheet        corresponding to a desired pattern of the black matrix by a        thermal image process using laser beam, thereby to melt the        image component of the transfer layer of the donor sheet with        heating and to transfer the melted image component on the        substrate; and    -   filling an opening portion surrounded by the light shielding        partition pattern formed from the image component with ink        having a predetermined color using an ink-jet method, thereby to        form picture elements.

Further, the present invention provides an organic EL element comprisinga transparent substrate, a plurality of pixel electrodes disposed on apredetermined position of the substrate, a partition pattern forseparating adjacent pixel electrodes, at least one luminescent layerformed on the pixel electrodes, and a counter electrode formed on theluminescent layer, characterized in that:

-   -   the partition pattern on the substrate is formed by making the        transfer layer of the donor sheet of the present invention and        the surface of the substrate come closely into contact with each        other and transferring the image component of the transfer layer        of the donor sheet in a pattern corresponding to the partition        pattern by a thermal imaging process using laser beam.

The present invention also provides a method of producing an organic ELelement comprising a transparent substrate, a plurality of pixelelectrodes disposed on a predetermined position of the substrate, apartition pattern for separating adjacent pixel electrodes, at least oneluminescent layer formed on the pixel electrodes, and a counterelectrode formed on the luminescent layer, which comprises the steps of:

-   -   forming pixel electrodes in a predetermined pattern on the        surface of the substrate;    -   making the surface of the pixel electrodes side of the substrate        and a transfer layer of a donor sheet comprising a base, a        light-to-heat conversion layer, and the transfer layer        containing an image component which is molten by heating due to        an action of the light-to-heat conversion layer and transferred        to the substrate in a patterned form, said layers being formed        in order on the base, come closely into contact with each other;    -   irradiating laser beam from the base side of the donor sheet        corresponding to the partition pattern by a thermal image        process using laser beam, thereby to melt the image component of        the transfer layer of the donor sheet with heating and to pile        up the molten image component on the substrate; and    -   filling an opening portion surrounded by the formed partition        pattern with an organic material having a predetermined color        using an ink-jet method to form the luminescent layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view showing a typical construction of adonor sheet according to the present invention;

FIGS. 2A to 2C are a series of sectional views showing in sequence amechanism of transfer of an image pattern to an image receiving elementin the donor sheet of FIG. 1;

FIG. 3 is a sectional view showing one embodiment of a separation rib ofa color filter of the present invention formed by using the donor sheetof FIG. 1;

FIG. 4 is a sectional view showing one embodiment of a black matrix of aliquid crystal display device of the present invention formed by usingthe donor sheet of FIG. 1;

FIGS. 5A to 5E are a series of sectional views showing in sequence amethod of producing the separation rib of FIG. 3 according to thepresent invention;

FIGS. 6A to 6D are a series of sectional views showing in sequenceanother method of producing the separation rib of FIG. 3 according tothe present invention;

FIGS. 7A to 7D are a series of sectional views showing in sequence amethod of producing the black matrix of FIG. 4 according to the presentinvention in order; and

FIGS. 8A to 8G are a series of sectional views showing in sequence amethod of producing an organic EL element using a donor sheet of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Subsequently, the embodiments of the present invention will be describedwith reference to the accompanying drawings. In the description withreference to the following drawings, different part names are sometimesapplied to those of the same reference numerals for convenience's sake.

The donor sheet according to the present invention is used as an imageforming element so as to transfer an image pattern to an image receivingelement by a thermal imaging process (LITI method). FIG. 1 shows atypical construction of a donor sheet of the present invention. As shownin the drawing, a donor sheet 10 comprises a base 1, being formed inorder on the base 1, a light-to-heat conversion layer 2, an intermediatelayer 3 and a transfer layer 4 containing an image component which ismolten by heating due to an action of the light-to-heat conversion layer2 and transferred to an image receiving element (not shown) in apatterned form. The donor sheet of the present invention may also haveany additional layer, if necessary.

In the donor sheet according to the present invention, the base can beformed from various natural or synthetic materials as far as thematerial can meet the requirements to the donor sheet. The requirementsto this base include, for example, transmittance of laser beam and heatresistance (because heating is conducted by irradiation of laser beam totransfer the image component), and proper flexibility, lightness,handling property and mechanical strength (because the donor sheet isused by applying to the image receiving element and then peeled offafter use). Suitable base includes various plastic materials such aspolyester resin and the like. The thickness of the base can varydepending on details of the desired donor sheet and is usually within arange from about 0.01 to 2.54 mm.

The light-to-heat conversion layer (also referred to as LTHC layer)supported by the base has a function of converting optical energy fromlaser beam irradiation into thermal energy, thereby to melt an imagecomponent in a transfer layer adjacent to the light-to-heat conversionlayer via an intermediate layer and to transfer and adhere the meltedimage component to the surface of the image receiving element.Accordingly, the light-to-heat conversion layer is preferably made of alight absorbing material itself, such as carbon black, or made of alayer containing the light absorbing material dispersed therein.Furthermore, this light-to-heat conversion layer preferably contains aphotopolymerizable component for the purpose of curing. Suitablelight-to-heat conversion layer is, for example, a layer wherein aphotopolymerizable monomer or oligomer and a photopolymerizationinitiator are dispersed in a binder resin. Such a light-to-heatconversion layer can be usually formed, for example, by coating a resincomposition having a predetermined composition on the surface of a baseaccording to a conventional coating method such as spin-coating method,gravure printing method, die coating method or the like, and drying theresin composition. The thickness of the light-to-heat conversion layercan vary depending on details and effect of the desired donor sheet andis usually within a range from about 0.001 to 10 μm.

The intermediate layer existing between the light-to-heat conversionlayer and transfer layer has a function of enabling a uniformlight-to-heat conversion action of the light-to-heat conversion layer.Usually, the intermediate layer can be formed from a resin materialcapable of meeting the above-described requirements. Such anintermediate layer can be usually formed, for example, by coating aresin composition having a predetermined composition on the surface ofthe light-to-heat conversion layer according to a conventional coatingmethod such as spin-coating method, gravure printing method, die coatingmethod or the like, and drying the resin composition in the same manneras in the case of the light-to-heat conversion layer. The thickness ofthe intermediate layer can vary depending on details and effect of thedesired donor sheet and is usually within a range from about 0.05 to 10μm.

The transfer layer to be disposed as an outermost layer of the donorsheet of the present invention contains an image component which ismolten by heating due to an action of the light-to-heat conversion layerand transferred to the image receiving element in a patterned form, asdescribed above. Accordingly, the transfer layer plays a very importantrole in the donor sheet of the present invention. As described in detailhereinafter, the image component of the transfer layer must contain afluorine-containing compound and/or a silicone compound in an optimizedamount for the purpose of accomplishing excellent controlled inkrepellency, in addition to the component concerned directly to imageformation, i.e. component which is transferred to the image receivingelement and constitutes its separation member.

The transfer layer can transfer the image component contained therein tothe surface of the image receiving element at high contrast according tothe LITI method and adhere it as a transferred image pattern, and can beformed in any composition as far as any peel residue is not formed whenthe used donor sheet is peeled from the image receiving element.According to use of the image pattern to be formed from the imagecomponent, the composition suited for each use can be prepared. In casewhere the image pattern is used as a separation member, i.e. separationrib or partition pattern, on the black matrix of the liquid crystaldisplay device, or case where the image pattern is used both as theblack matrix and separation rib after imparting the light shieldingproperty to the image pattern, the composition of the transfer layer canbe changed considering the light shielding property. To improve thelight shielding property, a black pigment (e.g. carbon black, etc.) andother coloring pigments may be added in the enhanced amount or metalpowders may be added.

In any case, according to the present invention, the water repellencyand oil repellency in high level can be imparted to the transferredimage pattern and the adhesion of the image pattern to the surface ofthe image receiving element is good. That is, in the transfer layer ofthe present invention, a fluorine-containing compound, a siliconecompound or a mixture thereof as a ink repellent component is containedin the image component and, at the same time, the content of the inkrepellent component is controlled within an optimum range. When thecontent of the ink repellent component is too large, the adhesion to thebase is lowered. On the other hand, when the content is too small,sufficient water repellency and oil repellency can not be obtained.

Thus, according to the present invention, a colored image pattern withexcellent water repellency and oil repellency can be formed withoutimpairing the image receiving element or its adhesion to the base whenthe transfer layer is a colored ink layer containing a colored imagecomponent. In case where such a colored image pattern is formed on thebase and then another colored image pattern is formed from water-basedor oil-based ink at the area other than that of the colored imagepattern using a conventional technique such as printing method, ink-jetrecording method, brushing method or the like, two colored imagepatterns can be separately formed, effectively, thereby making itpossible to effectively prevent defects such as color mixture,unevenness of thickness or the like. In case where three-color ormulti-color colored image pattern is formed according to the sametechnique as described above, an initial colored image pattern derivedfrom the transfer layer can also be utilized as a partition pattern orseparation rib for separating the other colored image pattern (e.g.second and third colored image patterns).

In the present invention, various fluorine-containing compounds as theink repellent component can be contained in the image component so as toobtain the above-described functions and effects. Suitablefluorine-containing compound includes, but are not limited to, monomer,oligomer or polymer containing fluorine atoms in the molecule,fluorine-containing surfactant or the like. These fluorine-containingcompounds are preferably those which are compatible with or dispersed ina binder resin used as a portion of the image component in the transferlayer, e.g. acrylic resin or the like.

The amount of the above-described fluorine-containing compound to beadded to the image component can vary widely depending on the kind ofthe compound, but is preferably optimized according to a surface tensionof ink used for formation of the colored image pattern. Specifically,the amount is preferably within a range of not more than 10% by weight,based on the total amount of the image component.

In the practice of the present invention, the same amount of a siliconecompound can be used in place of the above-described fluorine-containingcompound or used in combination with it. Suitable silicone compoundincludes, but are not limited to, resins, rubbers, surfactants, couplingagents and the like which are based on an organic polysiloxane.

In the present invention, it is necessary to ensure the ink repellencyenhanced in the resulting transferred image pattern, i.e. waterrepellency and oil repellency. The term “ink repellency” used herein hasalmost the same meaning as that of “water repellency” defined inJapanese Unexamined Patent Publication (Kokai) No. 6-347637. That is,the “ink repellency” is defined by a relation between the surfacetension of the surface of the substrate of the image receiving elementto which image pattern is transferred, that of ink and that of thepartition pattern (e.g. black matrix, etc.). In the present invention,the following matters are required to obtain enhanced ink repellency:

-   -   (1) The following relationship: Critical surface tension of the        surface of substrate>Surface tension of ink>Critical surface        tension of partition pattern shall be satisfied;    -   (2) The critical surface tension of the partition pattern should        be smaller than 35 dyne/cm;    -   (3) The critical surface tension of the surface of the substrate        should be 35 dyne/cm or more; and    -   (4) Comparing the surface tension of ink with that of the        partition pattern or that of the surface of the substrate, a        difference should be 5 dyne or more.

The ink repellency required in the present invention can be defined fromanother point of view. Preferably, the ink repellency can be defined bya contact angle of the surface of the substrate with ink ejected from ahead of an ink-jet printer. When using solvent-based ink whose surfacetension is from 20 to 40 mN/m, the contact angle with ink is preferablywithin a range from 30 to 55°, and more preferably from 40 to 50°. Whenusing water-based ink having a surface tension of 40 to 55 mN/m, thecontact angle with ink is preferably within a range from 60 to 80°. Whenthe contact angle with ink to be used is smaller than theabove-described range, color mixture with the other color in adjacentpicture element area occurs and, therefore, a desired color filter cannot be produced. On the other hand, when the contact angle with ink tobe used is larger than the above-described range, color mixture with theother color in adjacent picture element area does not occur. However,ink retained in the picture element area comes into a state where thecenter portion is exclusively protuberant (concave state) and,therefore, the picture element center portion is protuberant as comparedwith the peripheral portion even after drying ink, resulting in colorspot.

A mechanism of transfer of the image component in the donor sheet of thepresent invention will be apparent from FIGS. 2A to 2C. FIGS. 2A to 2Care a series of sectional views showing in sequence a mechanism oftransfer of an image pattern to an image receiving element in the donorsheet of FIG. 1.

As shown in FIG. 2A, a donor sheet 10 having the same construction asthat of the donor sheet shown in FIG. 1 are prepared, and then thisdonor sheet and a substrate 11 are laid one upon another so that atransfer layer 4 and the substrate 11 as an image receiving element comeclosely into contact with each other. Then, the donor sheet 10 of theresulting laminate is irradiated with laser beam L from the side of thebase 1 in a predetermined pattern. The pattern of laser beam Lcorresponds to an image pattern to be transferred to the image receivingelement.

As a result of pattern irradiation of laser beam, optical energy isconverted into thermal energy by an action of a light-to-heat conversionlayer 2 adjacent to the base 1 of the donor sheet 10 and the resultingthermal energy is further evened by an action of an intermediate layer3. Therefore, as shown in FIG. 2B, an image component 14 contained inthe transfer layer 4 is molten by heating in a patterned form, and thentransferred and adhered to the substrate 11 as the image receivingelement.

FIG. 2C shows a transferred image pattern 7 formed on the substrate 11as described above. This image pattern 7 is made closely into contactwith the substrate through a strong force. Since this image pattern 7has sufficiently high ink repellency, oozing of ink to the other area orcolor mixture with the color of adjacent area can be prevented in casewhere ink is adhered to the non-image pattern area using an ink-jetrecording method. Accordingly, when using such a donor sheet, colormixture or unevenness of thickness of color stripe can be effectivelyprevented in the production of the color filter using the ink-jetrecording method.

Also, the present invention is directed to a color filter comprising atransparent substrate, a plurality of picture elements disposed at apredetermined position on the substrate, and a partition pattern forseparating adjacent picture elements. In such a color filter, thepartition pattern for separating adjacent picture elements (e.g.separation rib or black matrix) can be formed by making the transferlayer of the donor sheet of the present invention and the surface of thesubstrate come closely into contact with each other using the donorsheet of the present invention according to the above-describedtechnique, and transferring the image component of the transfer layer ofthe donor sheet in a pattern corresponding to the partition pattern by athermal imaging process using laser beam.

FIG. 3 is a sectional view showing one embodiment of a separation rib ofa color filter of the present invention formed by using the donor sheetof FIG. 1. As shown in the drawing, a partition pattern composed of ablack matrix 15 and a separation rib 7 is formed at a predetermined area(partition pattern area) of a substrate 11. Picture elements can beformed by applying ink 6 to a picture element area 8 by an ink-jetprinting method after forming the partition pattern.

FIG. 4 shows one modification of FIG. 3 and is a sectional view showingone embodiment of a black matrix of a liquid crystal display device ofthe present invention formed by using the donor sheet of FIG. 1. As isshown in the drawing, the black matrix 15 is omitted and thus theseparation 7 can also serve as a black matrix.

The color filters shown in FIGS. 3 and 4 can be preferably produced bythe steps shown in order in FIGS. 5A to 5E, FIGS. 6A to 6D and FIGS. 7Ato 7D. It will be appreciated that the embodiments shown in the drawingsare illustrative and various modifications and improvements may be madewithin the scope of the present invention.

FIGS. 5A to 5D are a series of sectional views showing in sequence amethod of producing the separation rib of FIG. 3 according to thepresent invention.

As shown in FIG. 5A, a transparent substrate 11 suited for production ofa color filter is provided. Suitable substrate includes various glasssubstrates used conventionally in this technical field, but atransparent plastic substrate can also be used, if necessary.

Then, the surface of the provided substrate 11 is coated with a thinfilm of a black matrix forming material, as shown in FIG. 5B. The usableblack matrix forming material includes, for example, metal or oxidethereof, such as chromium (Cr), chromium oxide (CrO₂) or the like. Thethin film of the black matrix forming material can be formed in apredetermined film thickness by using various film forming methodsincluding sputtering method, deposition method and the like. This thinfilm may be a single layer or a multi-layer of two or more layers. Thethickness of the black matrix forming material can vary widely, but ispreferably within a range from 0.01 to 1 μm, and more preferably from0.1 to 0.25 μm. In such way, a thin film 5 as a black matrix precursoris formed on the substrate 11.

As shown in FIG. 5C, the donor sheet 10 of the present invention isplaced on the substrate 11 via the thin film 5, and then they are laidon upon another so that the thin film-like black matrix forming material5 and a transfer layer (not shown) of the donor sheet 10 come closelyinto contact with each other.

Laser beam L is irradiated from the substrate side of the donor sheet 10in a pattern corresponding to a desired pattern of the black matrix by athermal imaging process using laser beam, and then an image component ofthe transfer layer of the donor sheet 10 is molten by heating andtransferred onto the thin film-like black matrix forming material 5.

As shown in FIG. 5D, there can be obtained an image component 7transferred on the surface of the thin film-like black matrix formingmaterial 5 of the substrate 11 in a patterned form. A matrix-likepattern of the image component 7 serves as a separation rib in thefinally obtained color filter and its thickness can vary widelydepending on the desired effect, but is preferably within a range from0.5 to 3.0 μm, and more preferably from 1.5 to 2.5 μm. The thickness ofless than 0.5 μm does not ensure a height of separation rib sufficientto receive ink, whereas the thickness of more than 3.0 μm causes areduction of flatness of the color filter produced upon drying offilter.

Using the matrix-like pattern of the image component 7 as a mask, theexposed thin film-like black matrix forming material 5 is removed byetching. As an etchant, various acids can be used or a dry etching mayalso be used, if necessary. The residue, which was not removed byetching, can be completely removed by a treatment such as washing or thelike.

As a result of the etching, as shown in FIG. 5E, there can be obtained asubstrate 11 having a partition pattern composed of a black matrix 15and a separation rib 7. The separation rib 7 used as the mask forformation of the black matrix 15 may also be removed by alkalinesolution washing or any other peeling techniques.

Subsequently, although not shown in the drawing, an opening portionsurrounded by a partition pattern formed of a separation rib and a blackmatrix forming material as a ground (this portion is referred to as apicture element area) is preferably filled with ink having apredetermined color by an ink-jet recording method, thereby to formpicture elements (see FIG. 3).

A color filter comprising a transparent substrate, a plurality ofpicture elements disposed on a predetermined position of the substrate,and a partition pattern for separating adjacent picture elements, as thecolor filter of the present invention, is obtained through processingsteps whose number is smaller than that of a conventional method, usinga simplified processing device. Since the separation rib 7 is superiorin ink repellency in this color filter, oozing of ink to the other areaor color mixture with the color of adjacent area can be prevented incase where picture elements are formed by filling the picture elementarea with ink using an ink-jet recording method.

FIGS. 6A to 6D are a series of sectional views showing in sequenceanother method of producing the separation rib of FIG. 3 according tothe present invention. The method shown in the drawing can be carriedout basically in the same manner as that shown in FIGS. 5A to 5Edescribed previously, except for changing the procedure of thetreatment.

First, as shown in FIG. 6A, a thin film-like black matrix 15 is formedon the surface of a prepared transparent substrate 11 in a predeterminedpattern. The black matrix 15 can be formed by depositing Cr in a form ofa thin film using a sputtering method.

Then, as shown in FIG. 6B, the surface of the black matrix 15 of thesubstrate 11 and a transfer layer (not shown) of the donor sheet of thepresent invention are made come closely into contact with each other.Furthermore, as shown in FIG. 6C, laser beam L is irradiated from thesubstrate side of the donor sheet 10 in a pattern corresponding to thepattern of the black matrix 15 by a thermal imaging process using laserbeam.

As a result of pattern irradiation of laser beam, the image component ofthe transfer layer of the donor sheet 10 can be melted by heating andthen piled up as a separation rib 7 on the black matrix 15, as shown inFIG. 6D. As a result, a partition pattern composed of the black matrix15 and the separation rib 7 disposed thereon is obtained.

Subsequently, as described previously with reference to FIG. 3, pictureelements are formed by filling an opening portion (picture element area)surrounded by the formed partition pattern with ink having apredetermined color using an ink-jet method. Therefore, a color filtercomprising a transparent substrate, a plurality of picture elementsdisposed on a predetermined position of the substrate, and a partitionpattern for separating adjacent picture elements can be obtained.

FIGS. 7A to 7D are a series of sectional views showing in sequence amethod of producing the black matrix of FIG. 4 according to the presentinvention. This method can also be carried out basically in the samemanner as those shown in FIGS. 5A to 5E and FIGS. 6A to 6D describedpreviously. In the case of this method, since the separation rib canalso act as the black matrix, it is essential that the composition ofthe image component of the transfer layer is determined so that thetransfer layer can provide a separation rib superior in light shieldingproperty. This description was stated previously in the item of thedonor sheet.

First, a transparent substrate 11 as shown in FIG. 7A is prepared, andthe substrate and donor sheet 10 of the present invention are laid oneupon another as shown in FIG. 7B. In this case, attention is paid sothat the surface of the substrate 11 and the transfer layer (not shown)of the donor sheet 10 come closely into contact each other.

Then, a thermal imaging process using laser beam is carried out. Thisprocess is carried out by irradiating laser beam L from the substrateside of the donor sheet 10 in a pattern corresponding to a desiredpattern of the black matrix, as shown in FIG. 7C. As a result of patternirradiation of laser beam, the image component of the transfer layer ofthe donor sheet 10 can be melted by heating and then transferred ontothe substrate. As shown in FIG. 7D, a light shielding partition pattern7 serving both as the black matrix and separation rib is formed.

Subsequently, although not shown, picture elements are formed by fillingan opening portion (picture element area) surrounded by the lightshielding partition pattern formed from the image component with inkhaving a predetermined color using an ink-jet method (see FIG. 4).

As a result, a color filter having excellent characteristics, comprisinga transparent substrate, a plurality of picture elements disposed on apredetermined position of the substrate, and a partition pattern forseparating adjacent picture elements, can be obtained by a very simpletechnique using a simplified processing device.

According to the present invention, organic EL elements or devices andother optical devices can be advantageously produced, in addition to theproduction of the color filters. As described above, the organic ELelement of the present invention comprises a transparent substrate, aplurality of pixel electrodes disposed on a predetermined position ofthe substrate, a partition pattern for separating adjacent pixelelectrodes, at least one luminescent layer formed on the pixelelectrodes, and a counter electrode formed on the luminescent layer, andis characterized in that the partition pattern on the substrate isformed by making the transfer layer of the donor sheet of the presentinvention and the surface of the substrate come closely into contactwith each other and transferring the image component of the transferlayer of the donor sheet in a pattern corresponding to the partitionpattern by a thermal imaging process using laser beam. In the organic ELelement of the present invention, the luminescent layer-is preferablyformed by forming the partition pattern, followed by applying an organicmaterial to a luminescent layer-forming area using an ink-jet system.

The organic EL element having partition pattern, i.e., partitioning wall(bank), according to the present invention may have a wide variety ofembodiments or structures, and accordingly they can be produced inaccordance with the different methods.

FIGS. 8A to 8G illustrate one embodiment of the organic EL element ofthe present invention, along with a production process thereof. Theorganic EL element of the present invention will be describedhereinafter referring to the illustrated element, to which the presentinvention should not be restricted.

The illustrated organic EL element is a full color organic EL elementwith three colors, and, as is illustrated, it can be produced by thestep (FIG. 8A) of forming pixel electrodes 21, 22 and 23 or atransparent substrate 24, the step (FIG. 8B) of conducting a LITI methodusing donor sheet 10 of the present invention, the step (FIG. 8C) offorming partitioning walls (banks) 25, the step (FIG. 8D) of patterningluminescent layers 26 and 27, made of an organic compound, on therespective pixel electrodes, the step (FIG. 8E) of forming a luminescentlayer 28, and the step (FIG. 8F) of forming a cathode 31. The formationof the luminescent layer 26 and 27 can be carried out by means of anink-jet method.

The transparent substrate 24 functions not only as a support but also asa surface through which light is taken out. Accordingly, the materialfor the transparent substrate 24 is selected by taking thelight-permeability, thermal stability and the like into consideration.As for examples of the material to be used for the transparentsubstrate, glass, transparent plastic or the like can be mentioned, andamong these materials, a substrate made of glass is particularlypreferable in view of its excellent heat resistance.

As is shown in FIG. 8A, first, pixel electrodes 21, 22 and 23 are formedon the transparent substrate 24. As for examples of methods of formingthese pixel electrodes, photolithography, vacuum deposition method,sputtering method and pyrosol method can be mentioned. Among thesemethods, the photolithography is particularly preferable. As for thesepixel electrodes, it is preferred that they are formed into transparentpixel electrodes. As for the materials constituting the transparentpixel electrodes, a tin oxide film, an ITO film and a composite oxidefilm of indium oxide and zinc oxide can be mentioned.

Next, as shown in FIG. 8C partitioning walls (banks) 25 are formed tofill the spaces between the pixel electrodes. In this way, it ispossible to improve the contrast, to prevent mixing of colors of theluminescent materials, and to prevent light from leaking between thepixels.

The formation of the partitioning walls 25 can be carried out inaccordance with the LITI method which was applied to the formation ofthe partition pattern in the above-described production of the colorfilter. That is, as is shown in FIG. 8C, a donor sheet 10 having thesame construction as that of the donor sheet shown in FIG. 1 areprepared, and then this donor sheet and a transparent substrate 24 arelaid one upon another so that a transfer layer and the substrate comeclosely into contact with each other. Then, the donor sheet 10 of theresulting laminate is irradiated with laser beam L from the side of thebase of the donor sheet in a predetermined pattern. The pattern of laserbeam L corresponds to a pattern of the partitioning walls 25 to betransferred to the transparent substrate 24.

As a result of pattern irradiation of laser beam, optical energy isconverted into thermal energy by an action of a light-to-heat conversionlayer adjacent to the base of the donor sheet 10 and the resultingthermal energy is further evened by an action of an intermediate layer.Therefore, an image component contained in the transfer layer is meltedby heating in a patterned form, and then transferred and adhered to thesubstrate 24. FIG. 8C shows a transferred pattern of the partitioningwalls 25 formed on the substrate 24. This pattern of the partitioningwalls 25 is made closely into contact with the substrate 24 through astrong force. Since this pattern has sufficiently high ink repellency,oozing of ink to the other area or color mixture with the color ofadjacent area can be prevented in case where ink is adhered to thenon-image pattern area using an ink-jet recording method. Color mixtureor unevenness of thickness of color stripe can be effectively preventedin the production of the color filter using the ink-jet recordingmethod.

As for the materials constituting the banks 25, no particular limitationis imposed, if they have a resistance to the solvent for the ELmaterial. For example, organic material such as acrylic resin, epoxyresin, photosensitive polyimide and the like; and inorganic materialsuch as liquid glass and the like can be mentioned. In this regard, itis to be noted that the banks 25 may be formed into a black resist whichis formed by mixing carbon black and the like into the above-mentionedmaterial. Of course, it is necessary that these materials satisfy therequirements for the donor sheet of the present invention.

Further, organic luminescent layers are formed respectively on the pixelelectrodes according to a predetermined pattern. In this case, it ispreferable to provide organic luminescent layers with three color types.In this connection, it is preferred that at least one layer among theseorganic luminescent layers is formed by an ink-jet method.

In the illustrated embodiment, a red luminescent layer 26 and a greenluminescent layer 27 are formed on the pixel electrodes 21 and 22,respectively, by the ink-jet method. That is, as is shown in FIG. 8D, apixel of one of the three primary colors including red, green and blueor a pixel of at least one color which is intermediate between theprimary colors is formed by dissolving or dispersing a droplet 6 of theluminescent material in a solvent to obtain a discharge liquid and thendischarging a droplet 6 of the discharge liquid from a head of anink-jet device (not shown).

According to such an ink-jet method, it is possible to carry out finepatterning in a simple manner and in a short time. Further, it is alsopossible to control easily and freely the luminescent characteristicssuch as color balance and brightness (luminance) by adjusting thethickness of the layer through adjustment of the discharge amount of theink or by adjusting the ink concentration.

When the organic luminescent materials are conjugated polymerprecursors, the luminescent layers are formed by discharging theluminescent materials by the ink-jet method to carry out patterning, andthen conjugating (to form a film) the precursor components by heating orirradiation with light or the like.

Next, as shown in FIG. 8E, a blue luminescent layer 28 is formed on thered luminescent layer 26, the green luminescent layer 27 and the pixelelectrode 23. In this way, it is possible not only to form layers havingthe three primary colors including red, green and blue, but also to burythe level differences between the banks 25 and each of the redluminescent layer 26 and the green luminescent layer 27 so as to beflattened.

No particular limitation is imposed upon the forming method for the blueluminescent layer 28, and it is possible to form the layer using thegeneral film forming method known as deposition method or wet method,for instance, or using the ink-jet method.

Further, the blue luminescent layer 28 can be formed of an electroninjection and transfer material such as aluminum quinolynol complex. Inthis case, it is possible to promote the injection and transfer of thecarriers so as to improve the luminous efficiency. Furthermore, whensuch a blue luminescent layer 28 is laminated with red and greenluminescent layers formed of a hole injection and transfer material, itis also possible to inject and transfer the electrons and the holes fromthe respective electrodes into these laminated luminescent layers withappropriate balance, thereby enabling to improve the luminousefficiency.

In the illustrated embodiment, organic luminescent layers for two colorsare formed by the ink-jet method while the layer for the remaining onecolor is formed by a different method. Therefore, according to thisembodiment, even when a luminescent material which is not so suited forthe ink-jet method is used, a full color organic EL element can beformed by using such a material in a combination with other organicluminescent materials that are suited for the ink-jet method, so thatthe latitude in the design for the EL element will be expanded. Ofcourse, if desired, all the luminescent layers may be formed by theink-jet method.

Finally, as is shown in FIG. 8F, a cathode (a counter electrode) 31 isformed, thereby the organic EL element of the present invention iscompleted. In this case, it is preferred that the cathode 31 is formedinto a metallic thin film electrode, and as for examples of the metalfor forming the cathode, Mg, Ag, Al, Li and the like can be mentioned.In addition, a material having small work function can be used for thematerial for the cathode 31, and for example, alkali metal, alkali earthmetal such as Ca and the like, and alloys containing these metals can beused. Such a cathode 31 may be formed using a deposition method, asputtering method or the like.

Further, as shown in FIG. 8G, a protective film 32 may be formed on topof a cathode 31. By forming such a protective film 32, it becomespossible to prevent deterioration, damage, peeling and the like fromoccurring in the cathode 31 and in the luminescent layers 26, 27 and 28.As for materials for constructing the protective film 32, epoxy resin,acrylic resin, liquid glass and the like can be mentioned. Further, asfor examples of the forming method for the protective film 32, spincoating method, casting method, dipping method, bar coating method, rollcoating method, capillary method and the like can be mentioned.

In this embodiment, it is preferable that the luminescent layers areformed of an organic compound, and it is more preferable that theseluminescent layers are formed of a polymer organic compound. Byproviding such luminescent layers that are formed of the organiccompound, it is possible to obtain high brightness surface luminescenceat low voltages. Further, since luminescent materials can be selectedfrom wide range of field, a rational design for the luminescent elementbecomes possible. In particular, polymer organic compounds have anexcellent film formation property, and the luminescent layers composedof polymer organic compounds have an extremely good durability. Further,these polymer organic compounds have a band gap in the visible regionand a relatively high electrical conductivity. Among such polymerorganic compounds, a conjugated polymer can exhibit such propertiesprominently.

As for materials for the organic luminescent layers, polymer organiccompound itself, precursor of conjugated organic polymer compound whichis to be conjugated (to form a film) by heating or the like, and othermaterials are used.

In the above descriptions referring to the attached drawings, use of thedonor sheet of the present invention in the formation of the separationribs of the color filter, black matrix of the liquid crystal displaydevice and partitioning walls of the organic EL element according to theLITI method was explained in detail, however, it should be noted thatthe donor sheet of the present invention can be advantageously appliedto the formation of other separation members. In particular, the donorsheet of the present invention is noticeable, because it can be used toform separation members for all the materials capable of being patternedin accordance with the ink-jet method.

EXAMPLES

The present invention will be described by way of the examples thereof.It is appreciated that the present invention is not limited to thefollowing examples.

Example 1

(1) Production of Donor Sheet

A donor sheet comprising a base, a light-to-heat conversion layer, anintermediate layer and a transfer layer, said layers being formed on thebase, was produced according to the following procedure.

After a polyethylene terephthalate (PET) film having a thickness of 75μm was prepared as a base, a light-to-heat conversion layer (LTHClayer), an intermediate layer and a transfer layer each having thefollowing composition and film thickness were formed in the order asdescribed below. The (LTHC layer) and the intermediate layer were coatedwith die coating method, followed by being cured by irradiation withultraviolet rays, and then the transfer layer was similarly formed withdie coating method. Light-to-heat conversion layer Carbon black 100.0%by weight (trade name: “Raben 760”, manufactured by Colombian CarbonCo.) Dispersant  8.9% by weight (trade name: “Disperbyk 161”,manufactured by BYK-Cheimie Co.) Vinyl butyral resin  17.9% by weight(trade name: “Burvar B-98”, manufactured by Nippon Monsanto Co.)Carboxyl group-containing  53.5% by weight acrylic resin (trade name:“Joncryi 67”, manufactured by Jonson Polymer Co.) Acrylic oligomer834.0% by weight (trade name: “Evecryl EB629”, manufactured by UCBRadcure Co.) Carboxyl group-containing 556.0% by weight acrylic resin(trade name: “Elvacite 2669”, manufactured by ICI Co.)Photopolymerization initiator  45.2% by weight (trade name: “Irgacure369”, manufactured by Ciba Geigy Co.) Photopolymerization initiator 6.7% by weight (trade name: “Irgacure 184”, manufactured by Ciba GeigyCo.) Total 1622.3% by weight Solid content: 30% in PMA:MEK = 60:40Film thickness: 5 μm

Intermediate layer Vinyl butyral resin  4.76% by weight (trade name:“Burvar B-98”, manufactured by Nippon Monsanto Co.) Carboxylgroup-containing 14.29% by weight acrylic resin (trade name: “Joncryi67”, manufactured by Jonson Polymer Co.) Acrylic monomer 79.45% byweight (trade name: “Sartomer 351”, manufactured by Sartomer Co.)Photopolymerization initiator  4.50% by weight (trade name: “Irgacure369”, manufactured by Ciba Geigy Co.) Fluorescent dye  1.12% by weightTotal 104.12% by weight Solid content: 9.3% in IPA:MEK = 90:10Film thickness: 1 μm

Transfer layer Pigment, Dioxane Violet  50.0% by weight (trade name:“Hostaperum Violet RL NF”, manufactured by BASF Co.) Pigment,Disazoyellow  50.0% by weight (trade name: “ECY-204”, manufactured byDainippon Seika Industries Co.) Dispersant  15.0% by weight (trade name:“Disperbyk 161”, manufactured by BYK-Cheimie Co.) Carboxylgroup-containing 268.8% by weight acrylic resin (trade name: “CARBOSETGA1162”, manufactured by B.F. Goodrich Co.) Fluororesin  0.05% by weight(trade name: “FC55/35/10”, manufactured by 3M Co.) Epoxy crosslinkingagent 111.1% by weight (trade name: “SU8”, manufactured by ShellChemical Co.) Total 497.44% by weight Solid content: 13.5% in PMA:MIBK:BC = 60:30:10BC = butylcellosolveFilm thickness: 2.0 μm(2) Production of Black Matrix

Using an exclusive LITI machine (laser beam thermal transfer machine,wavelength of laser beam: 1064 nm), a black matrix was produced on aglass substrate. The donor sheet produced in the previous step and theglass substrate were laid one upon another, and then laser beam wasirradiated in a striped form under the conditions of an output of 11 W,a scan speed of 15 m/s and an irradiation width of 20 μm. Then, bakingwas conducted in an oven at 230° C. for 1 hour so as to cure and makethe transfer portion come closely into contact. As a result, a blackmatrix having a width of 20 μm and a thickness of 2.0 μm was formed onthe glass substrate.

[Evaluation Test]

Determination of contact angle and critical surface tension:

To evaluate an ink repellency of the black matrix (partition pattern)produced in accordance with the above-described process, a contact angleof the pattern with ink was determined. The contact angle was 65° asshown in the following Table 1. Further, a critical surface tension wascalculated from the contact angles with different solvents in each ofthe opening area, surrounded by the partition pattern, and the patternarea. As is shown in the following Table 1, the critical surface tensionwas

-   -   55 dyne/cm in the opening area, and    -   33 dyne/cm in the pattern area.

Note that a water-based color ink (red, green and blue; surface tension45 dyne/cm) was used in the above determination.

Determination of color mixture and color spot in the color filter:

Using the glass substrate with black matrix (partition pattern) producedin accordance with the above-described process, a color filter wasproduced to evaluate color mixture and color spot in each pictureelement area of the filter.

Using the ink jet printing device, water-based color ink (red, green andblue) was poured into each of the opening areas on the glass substratehaving the previously produced partition patter to form red, green andblue colored areas, followed by drying at 200° C. for 10 minutes. Ineach of the thus produced red, green and blue picture element areas,presence or absence of color mixture and color spot was observed byusing an optical microscope and a microscopic spectrometer. The presenceor absence of color mixture was evaluated from the migration of ink intothe adjacent picture element area. With regard to the color spot,samples where no color spot was observed were rated “good (⊙)”, sampleswhere color spot was slightly observed, but permissible were rate “fair(◯)”, and samples where severe color spot was observed were rated “bad(×)”. For the samples showing color mixture, the observation of thecolor spot was omitted. As is shown in the following Table 1, no colormixture observed and the color spot was rated “fair” in this example.

Example 2

The procedure of Example 1 was repeated with the proviso that, in thisexample, a glass substrate with chromium (Cr) black matrix (hereinafter,referred to as “CrBM”) was used in place of the glass substrate, and aseparation rib was produced on the black matrix of the substrate inaccordance with the following method.

Using an exclusive LITI machine (laser beam thermal transfer machine,wavelength of laser beam: 1064 nm), a separation rib was laid on a glasssubstrate provided with a black matrix. The donor sheet produced inExample 1 was laid on the black matrix side of the glass substrate, andthen laser beam was irradiated from the side of the donor sheet in thesame striped pattern as that of the black matrix under the conditions ofan output of 11 W, a scan speed of 15m/s and an irradiation width of 20μm. Then, baking was conducted in an oven at 230° C. for 1 hour so as tocure and adhere the transferred portion. A separation rib having a widthof 20 μm and a thickness of 2.0 μm was formed on the black matrix of theglass substrate.

The evaluation test similar to that of Example 1 was carried out usingthe resulting glass substrate with the partition pattern (black matrixplus separation rib). As shown in the following Table 1, the contactangle between the ink and the pattern was 65°, the critical surfacetension of the pattern was 33 dyne/cm, no color mixture was observed,and the color spot was rated “fair”.

Comparative Example 1

The procedure of Example 1 was repeated with the proviso that, in thisexample, for the comparison purpose, a solvent-based color ink (red,green and blue; surface tension 30 dyne/cm) was used in place of thewater-based ink.

The evaluation test similar to that of Example 1 was carried out usingthe resulting glass substate with the partition pattern (black matrix).As shown in the following Table 1, the contact angle was 7°, thecritical surface tension was 33 dyne/cm, and color mixture was observed.

Comparative Example 2

The procedure of Example 1 was repeated with the proviso that, in thisexample, for the comparison purpose, an amount of the fluororesin (tradename “FC55/35/10”, available from 3M Co.) added to the transfer layerwas changed from 0.05% by weight to 0.51% by weight.

The evaluation test similar to that of Example 1 was carried out usingthe resulting glass substate with the partition pattern (black matrix).As shown in the following Table 1, the contact angle was 88°, thecritical surface tension was 27 dyne/cm, no color mixture was observed,but the picture element had a convexity, and the color spot was rated“bad”.

Comparative Example 3

The procedure of Example 1 was repeated with the proviso that, in thisexample, for the comparison purpose, a solvent-based color ink was usedas in Comparative Example 1, and an amount of the fluororesin added waschanged to 0.51% by weight as in Comparative Example 2.

The evaluation test similar to that of Example 1 was carried out usingthe resulting glass substate with the partition pattern (black matrix).As shown in the following Table 1, the contact angle was 30°, thecritical surface tension was 27 dyne/cm, and color mixture was observed.

Example 3

The procedure of Example 1 was repeated with the proviso that, in thisexample, a solvent-based color ink was used as in Comparative Example 1,and an amount of the fluororesin added was changed from 0.05% by weightto 7.62% by weight.

The evaluation test similar to that of Example 1 was carried out usingthe resulting glass substate with the partition pattern (black matrix).As shown in the following Table 1, the contact angle was 45°, thecritical surface tension was 20 dyne/cm, no color mixture was observed,and the color spot was rated “good”.

Example 4

The procedure of Example 2 was repeated with the proviso that, in thisexample, a solvent-based color ink was used as in Comparative Example 1,and an amount of the fluororesin added was changed from 0.05% by weightto 7.62% by weight.

The evaluation test similar to that of Example 1 was carried out usingthe resulting glass substate with the partition pattern (black matrixplus separation rib). As shown in the following Table 1, the contactangle was 45°, the critical surface tension was 20 dyne/cm, no colormixture was observed, and the color spot was rated “good”.

Example 5

The procedure of Example 3 was repeated with the proviso that, in thisexample, a thickness of the baked transfer layer (that is, a height ofpattern) was changed from 2 μm to 1.6 μm.

The evaluation test similar to that of Example 1 was carried out usingthe resulting glass substate with the partition pattern (black matrix).As shown in the following Table 1, the contact angle was 45°, thecritical surface tension was 20 dyne/cm, no color mixture was observed,and the color spot was rated “good”.

Comparative Example 4

The procedure of Example 3 was repeated with the proviso that, in thisexample, for the comparison purpose, a thickness of the baked transferlayer (that is, a height of pattern) was changed from 2 μm to 0.9 μm.

The evaluation test similar to that of Example 1 was carried out usingthe resulting glass substate with the partition pattern (black matrix).As shown in the following Table 1, the contact angle was 45°, thecritical surface tension was 20 dyne/cm, and color mixture was observed.

Example 6

The procedure of Example 1 was repeated with the proviso that, in thisexample, a solvent-based color ink was used as in Comparative Example 1,and an amount of the fluororesin added was changed from 0.05% by weightto 10.16% by weight.

The evaluation test similar to that of Example 1 was carried out usingthe resulting glass substate with the partition pattern (black matrix).As shown in the following Table 1, the contact angle was 50°, thecritical surface tension was 18 dyne/cm, no color mixture was observed,and the color spot was rated “good”.

Comparative Example 5

The procedure of Example 1 was repeated with the proviso that, in thisexample, for the comparison purpose, a solvent-based color ink was usedas in Comparative Example 1, and an amount of the fluororesin added waschanged from 0.05% by weight to 55.00% by weight.

The evaluation test similar to that of Example 1 was carried out usingthe resulting glass substate with the partition pattern (black matrix).As shown in the following Table 1, the contact angle was 60°, thecritical surface tension was 15 dyne/cm, no color mixture was observed,but the picture element had a convexity, and the color spot was rated“bad”.

Example 7

The procedure of Example 3 was repeated with the proviso that, in thisexample, the BM substrate was used as in Example 2, in place of theglass substrate. The evaluation test similar to that of Example 1 wascarried out using the resulting glass substate with the partitionpattern (black matrix). As shown in the following Table 1, the contactangle was 45°, and the critical surface tension was 20 dyne/cm. TABLE 1Critical surface Pattern Contact tension³⁾ (dyne/cm) Height angle²⁾Opening Pattern Color Color Example No. Ink¹⁾ Substrate (μm) (°) areaarea mixture spot⁴⁾ Example 1 b) Glass 2 65 55 33 None ◯ Example 2 b)CrBM 2 65 55 33 None ◯ Comp. Ex. 1 a) Glass 2 7 55 33 Observed — Comp.Ex. 2 b) Glass 2 88 55 27 None X Comp. Ex. 3 a) Glass 2 30 55 27Observed — Example 3 a) Glass 2 45 55 20 None ⊚ Example 4 a) CrBM 2 4555 20 None ⊚ Example 5 a) Glass 1.6 45 55 20 None ⊚ Comp. Ex. 4 a) Glass0.9 45 55 20 Observed — Example 6 a) Glass 2 50 55 18 None ⊚ Comp. Ex. 5a) Glass 2 60 55 15 None X Example 7 a) BM 2 45 55 20 — —¹⁾a) Solvent-based ink (surface tension 30 dyne/cm); b) water-based ink(surface tension 40 dyne/cm)²⁾Contact angle of pattern with ink³⁾Determined from contact angle with different solvents⁴⁾⊚: good; ◯: fair; X: bad

As is seen from the results described in Table 1, according to thepresent invention, a black matrix or separation rib suited for producinga color filter by an ink-jet recording method can be produced in asimple technique. Furthermore, suitable ink repellency can be obtainedby controlling an amount of a fluororesin to be contained in an imagecomponent of a transfer layer. Further, in the resulting color filters,the generation of color mixture and color spot can be effectivelyprevented.

Industrial Applicability

As described above, according the present invention, there can beprovided a donor sheet, which can produce an separation member of anoptical element, e.g. partition pattern of a color filter, black matrixof a liquid crystal display device, and partitioning wall of the organicEL element by a shortened manufacturing step with ease and accuracy athigh contrast, and can impart excellent ink repellency, i.e. waterrepellency and oil repellency to the separation member. Use of thisdonor sheet has an effect capable of producing a color filter, a liquidcrystal display device, organic EL element and other optical elements atlow cost by a simple technique. It should be particularly noted that, onproviding such an optical element with a separation member, thesubstrate separation member can be provided by directly writing onto thesubstrate without using a complex method such as lithography method,like the prior art. The separation member of the optical element thusobtained, such as partition pattern, separation rib, black matrix,partitioning wall or the like, is suited for formation of pictureelements according to an ink-jet recording method because it isparticularly superior in ink repellency (water repellency and oilrepellency). Furthermore, since the amount of a fluorine-containingcompound and/or a silicone compound contained in the transfer layer ofthe donor sheet is optimized in the present invention, there is alsoexerted an effect capable of controlling the water repellency and oilrepellency of the separation member with maintaining the adhesion of theimage component (separation member) to be transferred to the imagereceiving element.

1. A donor sheet for transferring an image pattern to an image receivingelement by a thermal imaging process using laser beam, comprising abase, a light-to-heat conversion layer, and a transfer layer containingan image component which is melted by heating due to an action of thelight-to-heat conversion layer and transferred to the image receivingelement in a patterned form, said layers being formed in order on thebase, characterized in that: the image component of the transfer layercontains an ink-repellent or solvent-repellent compound in an optimizedamount.
 2. The donor sheet according to claim 1, which further comprisesan intermediate layer disposed between the light-to-heat conversionlayer and the transfer layer.
 3. The donor sheet according to claim 1,wherein the transfer layer contains an fluorine-containing compoundand/or a silicone compound.
 4. A color filter comprising a transparentsubstrate, a plurality of picture elements disposed on a predeterminedposition of the substrate, and a partition pattern for separatingadjacent picture elements, characterized in that: the partition patternon the substrate is formed by making the transfer layer of the donorsheet of claim 1 and the surface of the substrate come closely intocontact with each other and transferring the image component of thetransfer layer of the donor sheet in a pattern corresponding to thepartition pattern by a thermal imaging process using laser beam.
 5. Thecolor filter according to claim 4, wherein the picture elements areformed by forming the partition pattern and applying ink to a pictureelement forming area using an ink-jet system.
 6. The color filteraccording to claim 4, wherein the partition pattern is a black matrix ofa liquid crystal display device.
 7. A method of producing a color filtercomprising a transparent substrate, a plurality of picture elementsdisposed on a predetermined position of the substrate, and a partitionpattern for separating adjacent picture elements, which comprises thesteps of: forming a thin film-like black matrix in a predeterminedpattern on the surface of the substrate; making the surface of the blackmatrix side of the substrate and a transfer layer of a donor sheetcomprising a base, a light-to-heat conversion layer, and the transferlayer containing an image component which is melted by heating due to anaction of the light-to-heat conversion layer and transferred to thesubstrate in a patterned form, said layers being formed in order on thebase, come closely into contact with each other; irradiating laser beamfrom the base side of the donor sheet corresponding to the pattern ofthe black matrix by a thermal image process using laser beam, thereby tomelt the image component of the transfer layer of the donor sheet withheating and to pile up the molten image component on the black matrix;and filling an opening portion surrounded by the formed partitionpattern with ink having a predetermined color using an ink-jet method.8. The method according to claim 7, wherein the donor sheet 3 transfersan imaging pattern to an image receiving element by a thermal imagingprocess using laser beam, comprising a base, a light-to-heat conversionlayer, and a transfer layer containing an image component which ismelted by heating due to an action of the light-to-heat conversionlayers and transferred to the image receiving element in a patternedform, said layers being formed in order on the base, characterized inthat: the image component of the transfer layer contains anink-repellent or solvent-repellent compound in an optimized amount.
 9. Amethod of producing a color filter comprising a transparent substrate, aplurality of picture elements disposed on a predetermined position ofthe substrate, and a partition pattern for separating adjacent pictureelements, which comprises the steps of: coating the surface of thesubstrate to form a thin film of a black matrix forming material; layingthe substrate and a donor sheet comprising a base, a light-to-heatconversion layer, and a transfer layer containing an image componentwhich is melted by heating due to an action of the light-to-heatconversion layer and transferred to the substrate in a patterned form,said layers being formed in order on the base, one upon another so thatthe thin film-like black matrix forming material and the transfer layerof the donor sheet come closely into contact with each other;irradiating laser beam from the base side of the donor sheetcorresponding to a desired pattern of the black matrix by a thermalimage process using laser beam, thereby to melt the image component ofthe transfer layer of the donor sheet with heating and to transfer themelted image component on the thin film-like black matrix formingmaterial; removing the exposed black matrix forming material by etchingusing, as a mask, the image component transferred to the surface of thethin film-like black matrix forming material of the substrate in apatterned form; and filling an opening portion surrounded by thepartition pattern formed from the image component and black matrix as aground thereof with ink having a predetermined color using an ink-jetmethod, thereby to form picture elements.
 10. The method according toclaim 9, wherein the donor sheet transfers an imaging pattern to animage receiving element by a thermal imaging process using laser beam,comprising a base a light-to-heat conversion layer, and a transfer layercontaining an image component which is melted by heating due to anaction of the light-to-heat conversion layers and transferred to theimage receiving element in a patterned form, said layers being formed inorder on the base, characterized in that: the image component of thetransfer layer contains an ink-repellent or solvent-repellent compoundin an optimized amount.
 11. A method of producing a color filtercomprising a transparent substrate, a plurality of picture elementsdisposed on a predetermined position of the substrate, and a lightshielding partition pattern for separating adjacent picture elements,which comprises the steps of: laying the substrate and a donor sheetcomprising a base, a light-to-heat conversion layer, and a transferlayer containing an image component which is melted by heating due to anaction of the light-to-heat conversion layer and transferred to thesubstrate in a patterned form, said layers being formed in order on thebase, one upon another so that the thin surface of the substrate and thetransfer layer of the donor sheet come closely into contact with eachother; irradiating laser beam from the base side of the donor sheetcorresponding to a desired pattern of the black matrix by a thermalimage process using laser beam, thereby to melt the image component ofthe transfer layer of the donor sheet with heating and to transfer themolten image component on the substrate; and filling an opening portionsurrounded by the light shielding partition pattern formed from theimage component with ink having a predetermined color using an ink-jetmethod, thereby to form picture elements.
 12. The method according toclaim 11, wherein the donor sheet transfers an imaging pattern to animage receiving element by a thermal imaging process using laser beam,comprising a base, a light-to-heat conversion layer, and a transferlayer containing an image component which is melted by heating due to anaction of the light-to-heat conversion layers and transferred to theimage receiving element in a patterned form, said layers being formed inorder on the base, characterized in that: the image component of thetransfer layer contains an ink-repellent or solvent-repellent compoundin an optimized amount.
 13. An organic EL element comprising atransparent substrate, a plurality of pixel electrodes disposed on apredetermined position of the substrate, a partition pattern forseparating adjacent pixel electrode, at least one luminescent layerformed on the pixel electrodes, and a counter electrode formed on theluminescent layer, characterized in that: the partition pattern on thesubstrate is formed by making the transfer layer of the donor sheet ofclaim 1, and the surface of the substrate come closely into contact witheach other and transferring the image component of the transfer layer ofthe donor sheet in a pattern corresponding to the partition pattern by athermal imaging process using laser beam.
 14. The organic EL elementaccording to claim 13, wherein the luminescent layer is formed byforming the partition pattern and applying an organic material using anink-jet system.
 15. A method of producing an organic EL elementcomprising a transparent substrate, a plurality of pixel electrodesdisposed on a predetermined position of the substrate, a partitionpattern for separating adjacent pixel electrodes, at least oneluminescent layer formed on the pixel electrodes, and a counterelectrode formed on the luminescent layer, which comprises the steps of:forming pixel electrodes in a predetermined pattern on the surface ofthe substrate; making the surface of the pixel electrodes side of thesubstrate and a transfer layer of a donor sheet comprising a base, alight-to-heat conversion layer, and the transfer layer containing animage component which is melted by heating due to an action of thelight-to-heat conversion layer and transferred to the substrate in apatterned form, said layers being formed in order on the base, comeclosely into contact with each other; irradiating laser beam from thebase side of the donor sheet corresponding to the partition pattern by athermal image process using laser beam, thereby to melt the imagecomponent of the transfer layer of the donor sheet with heating and topile up the molten image component on the substrate; and filling anopening portion surrounded by the formed partition pattern with anorganic material having a predetermined color using an ink-jet method toform the luminescent layer.
 16. The method according to claim 15,wherein the donor sheet transfers an imaging pattern to an imagereceiving element by a thermal imaging process using laser beam,comprising a base, a light-to-heat conversion layer, and a transferlayer containing an image component which is melted by heating due to anaction of the light-to-heat conversion layers and transferred to theimage receiving element in a patterned form said layers being formed inorder on the base, characterized in that: the image component of thetransfer layer contains an ink-repellent or solvent-repellent compoundin an optimized amount.